Calculate the molarity of water if it's density is 1000 kg/m³

Wavelength of high energy transition of H-atoms is 91.2 nm. Calculate the corresponding wavelength of He atoms.

Using VSEPR theory deduce the structures of PCl₅ and BrF₅

1 gm of charcoal adsorbs 100 ml 0.5 M CH₃COOH to form a monolayer, and thereby the molarity of CH₃COOH reduces to 0.49. Calculate the surface area of the charcoal adsorbed by each molecule of acetic acid. Surface area of charcoal = 3.01 $$\times$$ 10² m²/gm.